1. Field of the Invention
The invention concerns a signalling processing system relating to equipment made available to users for a circuit mode system which is constructed around units interconnected by a local area network of point-to-point temporal circuits in a telecommunications installation, these units being employed among other things to connect equipments made available to users in the installation, possibly to connect auxiliary devices and/or to connect control or processing equipments of the installation.
2. Description of the Prior Art
French patent application 2 665 314 describes an interconnect network for an integrated services digital telecommunication installation core in which the core units are interconnected by point-to-point circuits which are organized according to the specific requirements of the units connected. This interconnect network includes a subnetwork interconnecting the circuit mode units of the installation core, i.e. those involved directly or indirectly in synchronous time-division switching, in the installation, of information transferred successively in the form of binary blocks of the same size, a block usually consisting of one byte and the transfer period being 125 .mu.s in the usual case of switching 64 kbit/s circuits.
This enables the transfer of structured information at 8 kHz, including transmission of speech or other audio frequency signals sampled and coded in the form of bytes and the transmission of data also in the form of bytes.
The units concerned include those found in telecommunication installations including those used to connect various user equipments and/or to connect associated auxiliary units and those formed by a control or processing equipment.
The units for connecting user equipments are, for example, of the telephone interface controller type, interface controllers for telecommunication equipments connectable to S0/T0 or S2/T2 interfaces as defined by the CCITT, and interface controllers for dedicated user equipments, i.e. equipments used according to a specific standard implemented in the installation in question.
In the known manner, the analogue and digital user equipments of an installation are connected to the installation by interface circuits, as mentioned above. These interface circuits enable transit of information exchanged on demand between the equipments through the installation to which these equipments are directly connected or at least able to be connected.
In the known manner exchanges of information between user equipments in particular between each equipment and the interface circuit by means of which it is connected to the installation, involve exchanges of signalling. It is the same when these equipments communicate with an auxiliary unit connected to an interface controller or to a control or processing equipment of the installation. Exchanges of signalling involving a user equipment are governed by a specific protocol which can be processed by this type of equipment.
To this end each user equipment includes a logic system for processing signalling information received or to be transmitted, using a given protocol, and the same must apply at the interface controller to which it is connected. Given the wide variety of communication requirements, there are many types of user equipment which may co-exist within the same installation, which may therefore have to support different protocols simultaneously.
Each interface controller circuit therefore includes input/output interface modules at which the transmission circuits connecting it to each of the user equipments that it serves terminate. Each of these modules is designed and/or possibly programmed according to the characteristics of the transmission LINK it is to serve and the protocol that is to be used for exchanges of information using the LINK. Various modules are thus likely to be used conjointly in the interface circuits of one and the same installation, even in one and the same interface circuit.
The interface circuits usually include internal logic enabling them to process and/or steer signalling received from user equipment that they serve, via the interface modules to which these equipments are connected; this logic also enables the sending of signalling in the reverse direction through the interface module. As there is a wide variety of user equipments and consequently of protocols and interface modules, it is also necessary to provide interface circuit internal logic capable of adapting to the various foreseeable variants, if possible in a simple, flexible and low-cost manner.